JPS57115994A - Method for controlling circumferential length of spiral steel pipe - Google Patents

Abstract

PURPOSE: To control the circumferential length of spiral steel pipes with a higher accuracy, by measuring the circumferential length of spiral steel pipes in time series, by operating controlling amounts for modifying the circumferential length from the proportional term and the integral term of the deflection between the measured value and a target value, and by adjusting relative positions of spiral pipes and metallic strips at the welding point.

CONSTITUTION: A location of a piston rod 6_a which tighten a belt 2 wound round a spiral steel pipe SP is detected with a displacement detector 7 and the detected value is outputted to a circumferential length arithmetic unit 11. Moreover, a condition of an air cylinder 6 at an appropriate sampling time (t) is outputted from a control device 10 to the arithmetic unit 11 as a timing signal. Then, the circumferential length of the steel pipe SP is operated and inputted into a deflection arithmetic unit 12, and a difference ΔL_t between a target value for controlling and the measured value is operated. Thereafter, the circumferential length T_t in the time period between the last sampling time and the present sampling time is outputted to a modifying amount arithmetic unit 13 together with the difference ΔL_t. A modifying amount ΔH_t of auxiliary rolls 81 and 82 obtained through operations at the modifying amount arithmetic unit 13 is outputted to a control output device 14, and a necessary minimum modification of the auxiliary rolls 81 and 82 is made.

COPYRIGHT: (C)1982,JPO&Japio